Good, now all that's left is to find a good and safe way to permanently store antihydrogen.

Well they're getting there http://alpha-new.web.cern.ch/ . There also used to be another big antihydrogen experiment in Canada somewhere (TRIUMF probably?) a few years back but my quick google search only yielded ALPHA collaborators.

"The fact that we haven't seen any evidence of it tells us that either our understanding of it is incomplete, or it's a little different to what we thought - or maybe it doesn't exist at all," he said.

Back to the drawing board, in so many words, it seems. I wonder how this is going to affect the scientists in this field (as far as either trying harder to develop new experiments or throwing in the towel). These scientists have been trying to prove this for quite some time...I guess what i'm getting at here, is that it begs the question if "it's a little different to what we thought," is even possible to this situation.

Balderdash. They've done a good job of squashing a good number of models and some more speculative stuff but only ~2 inverse femtobarns (around 140 million million collisions, which sounds like a lot but really isn't in the case of the LHC) of data has been analyzed and they haven't even gone to full power yet. Even the most fervent of supersymmetry supporters probably wouldn't expect signs at this point. For a more balanced view (with a lot of interesting links) see http://profmattstrassler.com/2011/08/19 ... n-trouble/ .

Balderdash. They've done a good job of squashing a good number of models and some more speculative stuff but only ~2 inverse femtobarns (around 140 million million collisions, which sounds like a lot but really isn't in the case of the LHC) of data has been analyzed and they haven't even gone to full power yet. Even the most fervent of supersymmetry supporters probably wouldn't expect signs at this point. For a more balanced view (with a lot of interesting links) see http://profmattstrassler.com/2011/08/19 ... n-trouble/ .[/quote]That's why I included the "probably" there. I know it's not yet the official death of the theory, even if the article is quite critical, and I am the first one to recognize the holes in my own knowledge on these matters, but it would be interesting to see what the physicists will cook up if it turns out there's something wrong in the models we have.

Supersymmetry is, if I've understood correctly, one of the really nifty-looking models that rely on assumptions and would be very, very cool if it really worked.

But they have found that is not so and it appears everything is actually speeding up, accelerating away which they put down to "dark energy" (different from dark matter). Maybe all matter travelling at colossal speed encounters other regions we yet know nothing about?

No, this is a misunderstanding of how the universe expands. Many people imagine this expansion as galaxies and the like flying out into empty space beyond the universe, but this is incorrect. The universe encompasses all space and time, there is no region outside of it to expand into (ignoring theories of multiple universes for the sake of this explanation, but in any case these other universes would not be simply far away regions that you get to by flying for a long time). Rather, it is space itself that is expanding; the universe is stretching if you will, its internal distances increasing.

A popular analogy is that of a balloon on which you draw a few dots while it's not inflated, then as you blow air into the balloon you can observe that the dots are all "moving" away from each other, even though they're not really going anywhere - it's the balloon's surface between them that is stretching. So it is with the universe; objects are observed to be moving away from each other as the space between them itself is expanding. It's an imperfect analogy of course; the balloon is a two-dimensional surface and it's expanding into the air around it, while the universe has three spatial dimensions, but hopefully you get the idea.

This phenomenon is only effective on very large scales at present time, like in the space between galactic superclusters. On more local scales, like in groups of galaxies, or galaxies themselves, or here on Earth, matter is still very much attracted together by gravity and other forces. It is thought that due to the accelerating nature of universal expansion though, this will not always be the case and this is what would lead to the universe's "heat death". As the force of expansion increases, previously gravity-bound galaxies will start to move away from each other, then those galaxies themselves will be shredded as the stars forming them fly apart, and eventually even the stars and planets are ripped open as the expansion overcomes local gravity. In the end, the very protons and other particles constituting matter are also driven apart until there is practically no energy left in the universe. A cheerful perspective, but of course that all happens over mind-bogglingly enormous time scales.

If you're curious about such end-time scenarios, I'd recommend reading Phil Plait's excellent Death from the Skies, which examines the science and likeliness of various events that would end the Earth, the Sun, and the Universe.

2conan4u wrote:

i've read that the universe is basically sling shot outwards, like throwing a stone up, eventually the forces will pull it all back towards the start/beginning of it all again as it loses the initial velocity that shot it out to begin with collapsing in again on the single force at the center.

That used to be a popular hypothesis, but it has increasingly fallen out of favor since the 1998 discovery that the expansion of the universe is actually accelerating, rather than slowing down for a "Big Crunch" kind of end. The scenario I described above now seems more likely based on current knowledge.

That's why I included the "probably" there. I know it's not yet the official death of the theory, even if the article is quite critical, and I am the first one to recognize the holes in my own knowledge on these matters, but it would be interesting to see what the physicists will cook up if it turns out there's something wrong in the models we have.

Supersymmetry is, if I've understood correctly, one of the really nifty-looking models that rely on assumptions and would be very, very cool if it really worked.

There's actually some pretty good layman level explanations of supersymmetry in the other articles on that site I linked to. But my point was just that there's still a LONG way to go before we can even say most of the most viable supersymmetry models are because other than the hope that supersymmetry solves the hierarchy problem (constraining most of the particle masses around the 1 TeV area) there's no way to predict how heavy superpartners might actually be.

Actually, why supersymmetry is so special is because it's just about the only exception to the old Coleman-Mandula Theorem that showed you can't mix the symmetries of your background spacetime with the internal symmetries of the fields you're putting on it in any but the most trivial way. At the time (late 60s if I recall) it was a pretty big deal and killed a lot of ideas. And it turned out that this exception had a lot of cool results and might solve some serious problems.

But the article is somewhat right in the sense that if there is in fact no supersymmetry, there's not a lot of wiggle room in that area for similar ideas. It'll have to be completely different. What the article gets completely wrong though is that supersymmetry is waning and technicolor is making some kind of comeback whereas it's actually getting hit harder by this new data.

Can't say we didn't see this coming. It has been a problem for years, and it's only growing. Let's hope we do not obstruct humanity's chances of exploring space by crapping up the lower Earth orbit with debris.

Can't say we didn't see this coming. It has been a problem for years, and it's only growing. Let's hope we do not obstruct humanity's chances of exploring space by crapping up the lower Earth orbit with debris.

Not that I'm particularly knowledgeable in the field, far from it, but I would imagine it wouldn't be too hard to send a heavily reinforced superconducting magnet up there to catch a lot of the stuff. Although I imagine a big problem would be that all the debris is metal and mostly moving very fast so that as they approached the magnet would feel huge variations in magnetic field strength which would cause massive eddy currents which would then release tons of heat and damage the spacecraft.

EDIT: Thinking this through a bit more, the Eddy currents would also massively slow down the debris so as long as this superconducting net of a spacecraft were decently reinforced and highly heat resistant it could work.

Still though this doesn't bother me as I don't find most space exploration to be particularly useful, which is rather ironic since my physics work is pretty much completely useless to anyone other people doing other useless things. Although we cost less than a spacecraft.

I was watching The Discovery channel last night and the show that Morgan Freeman narrates.It was talking about black and white holes. If I got this correct some Polish physicist (not sure) is saying that a black hole leads to white holes in a parallel universe or creates a whole new universe every time a star collapses which in turn is another big bang. Did I get ant of that right? My brain kinda of melts when I hear theories like that for the fist time. It usually takes a few listens to absorb such complicated shit. Anyways,I found this to be real interesting. Anybody else watch this or know more about the subject matter. Also they were saying that dark matter is proof of multi universes due to the discovery of dark matter. Being that the gravitational pull proves it as such. Or something like that.Wow,mental overload!

If I got this correct some Polish physicist (not sure) is saying that a black hole leads to white holes in a parallel universe or creates a whole new universe every time a star collapses which in turn is another big bang. Did I get ant of that right?

It's a theory that has been hypothesized by a few physicists, but as far as I know the prevalent idea is that anything that travels into a black hole is crushed into an atom, including light itself.

As much as I like the fantasy of going through a black hole and ending up in a parallel universe, it seems a bit too pie-in-the-sky to me.

_________________

TheRealThing wrote:

I took advantage of being in 8 feet of ocean water by taking an enormous dump in the water. I had goggles on so I watched it sink to the sand on the ocean floor. It was the most awe-inspiring thing I have ever seen.

I was watching The Discovery channel last night and the show that Morgan Freeman narrates.It was talking about black and white holes. If I got this correct some Polish physicist (not sure) is saying that a black hole leads to white holes in a parallel universe or creates a whole new universe every time a star collapses which in turn is another big bang. Did I get ant of that right?

This is wrong. White holes only show up in eternal black hole solutions, that is for simplicity we just assume the black hole has always been there since we usually only care about its properties after the black hole has formed and the actual collapse itself is unimportant. In a realistic collapse solution there is no white hole. Although this is an often repeated misconception.

hunglikemouse wrote:

Also they were saying that dark matter is proof of multi universes due to the discovery of dark matter. Being that the gravitational pull proves it as such. Or something like that.Wow,mental overload!

The gravitational pull you're talking about, I'm pretty sure, is our indirect evidence for dark matter. Indirect in the sense that we don't see the actual dark matter, but only their gravitational effect on things like the rotational velocities of galaxies. There are two camps here, people who think this is caused by unseen matter and our laws of physics are still correct on this scale (the far larger camp) and people who think the laws change on this scale, stuff like MOND theory, and dark matter doesn't exist. Although neither of these has anything to do with multiple universes.

Out of curiosity, what episode was this? Out of the couple I've seen they've been reasonably accurate, nothing like these blunders.

Last edited by Jigglefactor on Wed Sep 07, 2011 8:49 pm, edited 1 time in total.

A cheerful perspective, but of course that all happens over mind-bogglingly enormous time scales.

If you're curious about such end-time scenarios, I'd recommend reading Phil Plait's excellent Death from the Skies, which examines the science and likeliness of various events that would end the Earth, the Sun, and the Universe.

Thankyou, but I realise the futility now of trying to grasp a time when our Universe could fade away into a whimpering heat death, not an event mankind is ever going to be concerned with or any genitically enhanced space roaming descendants(?). A point Napero referred to earlier with "raised eyebrows" like anyone should concern themselves with this unimaginable event. I struggle imagining in scope a "simple" discovery like VY Canis Majoris.

SDSS J102915+172927 - The Star That Shouldn't Exist.

"This star has the composition that is the nearest that has been found up to now to the big bang composition"

According to the theory, this star should not have been able to form.

"But it did. One explanation is that that the star is indeed near-primordial and that its nursery was cooled by something other than carbon and oxygen, like interstellar dust".

If I got this correct some Polish physicist (not sure) is saying that a black hole leads to white holes in a parallel universe or creates a whole new universe every time a star collapses which in turn is another big bang. Did I get ant of that right?

It's a theory that has been hypothesized by a few physicists, but as far as I know the prevalent idea is that anything that travels into a black hole is crushed into an atom, including light itself.

You're correct that anything pulled in by a black hole's gravity is crushed, but it's not into the space of an atom. It's crushed into an infinitely small area called a singularity. What happens to matter and energy at a singularity is completely unknown. Physicists don't even have a clue as to what physical laws are present at a singularity. Matter cannot occupy the same area in space, so huge amounts of matter occupying an infinitely small area is just mind-boggling. The hypothesis hunglikemouse is referring to - that black holes send matter and energy to newly created universes - is very interesting and plausible.

Vlachos wrote:

As much as I like the fantasy of going through a black hole and ending up in a parallel universe, it seems a bit too pie-in-the-sky to me.

The fact that anything alive couldn't possibly survive a black hole should make it clear that humans couldn't travel through one and enter a new universe. That is indeed a fantasy. But matter and energy possibly could. Scientists don't really know.

There is something called "Hawking radiation" that is predicted to be emitted by black holes, which eventually causes them to shrink in mass and disappear, but the key word here is "predicted". I'm not sure if this has been verified. If someone can link me to an article about it I'd be grateful. It seems this would end the black hole/white hole hypothesis, but again, I'm not sure if Hawking radiation has been observed.

String theorists Neil Turok of Cambridge University and Paul Steinhardt, Albert Einstein Professor in Science and Director of the Center for Theoretical Science at Princeton believe that the cosmos we see as the result of a Big Bang was actually created by the cyclical trillion-year collision of two universes (which they define as three-dimensional branes plus time) that were attracted toward each other by the leaking of gravity out of one of the universes.In their view of the universe, the complexities of an inflating universe after a Big Bang are replaced by a universe that was already large. flat, and uniform with dark energy as the effect of the other universe constantly leaking gravity into our own and driving its acceleration.

According to this theory, the Big Bang was not the beginning of time but the bridge to a past filled with endlessly repeating cycles of evolution, each accompanied by the creation of new matter and the formation of new galaxies, stars, and planets.

Turok and Steinhardt were inspired by a lecture given by Burt Ovrut who imagined two branes, universes like ours, separated by a tiny gap as tiny as 10-32 meters. There would be no communictaion between the two universes except for our parallel sister universe's gravitational pull, which could cross the tiny gap.

Orvut's theory could explain the effect of dark matter where areas of the universe are heavier than they should be given everything that's present. With their theory, the nagging problems surrounding the Big Bang (beginning from what, and caused how?) are replaced by an eternal cosmic cycle where dark energy is no longer a mysterious unknown quantity, but rather the very extra gravitational force that drives the universe to universe (brane-brane) interaction.

You're correct that anything pulled in by a black hole's gravity is crushed, but it's not into the space of an atom. It's crushed into an infinitely small area called a singularity. What happens to matter and energy at a singularity is completely unknown. Physicists don't even have a clue as to what physical laws are present at a singularity.

Well we have some idea... Quantum gravity research has been going on for quite some time now.

Moravian_black_moon wrote:

Matter cannot occupy the same area in space, so huge amounts of matter occupying an infinitely small area is just mind-boggling.

Nit picky as I am, that's note quite right. It depends on what kind of matter you're talking about. You could easily have tons of bosonic matter occupying the same space (There's a lot of toy models out there of concentrating light, that is a bunch of bosons, into a single point to create singularities to test the cosmic censorship hypothesis). Fermionic matter on the other hand you couldn't, which is why neutron stars exist. Fermions (including neutrons) cannot occupy the same state (including position). This inability to be in the same state creates a sort of "pressure" that keeps the neutron star from collapsing on itself instead of the usual pressure coming from nuclear reactions that keeps other stars from collapsing in on themselves.

Moravian_black_moon wrote:

The hypothesis hunglikemouse is referring to - that black holes send matter and energy to newly created universes - is very interesting and plausible.

It's fun to think about but would actually violate some very principal laws of physics (it's a bit technical and not particularly plausible). Wormholes on the other hand could work, but we won't know until the physics of quantum gravity are understood.

Moravian_black_moon wrote:

There is something called "Hawking radiation" that is predicted to be emitted by black holes, which eventually causes them to shrink in mass and disappear, but the key word here is "predicted". I'm not sure if this has been verified. If someone can link me to an article about it I'd be grateful. It seems this would end the black hole/white hole hypothesis, but again, I'm not sure if Hawking radiation has been observed.

Hawking radiation hasn't been observed and it is unlikely to be observed any time soon. Hawking radiation is extremely faint and would be pretty much impossible to detect given the vast amount of other radiation that comes from around black holes. The only way we'd have a chance of detecting it would be that somehow we could create extremely small black holes in a controlled environment (the smaller it is, the quicker and more powerfully it evaporates and the less noise we get since it wouldn't be surrounded by all this interstellar junk). However, Hawking radiation is still widely believed to be correct since it comes from a combination of quantum field theory and general relativity generally called semi-classical gravity (that is you treat all the matter as quantum but still treat gravity classically) and both of these theories have been tested to be correct to extremely high precision.

Although, again, this has nothing to do with white holes who don't come out of solutions or simulations of realistic collapse. They're only a mathematical artifact that come out of using simpler solutions to study black holes.

hunglikemouse wrote:

stuff

Ah, all that Turok business. All this brane-brane interaction stuff is far ever being observed and my anecdotal experience tells me that most people disagree with cyclic cosmology in general, much less string theory inspired cyclic cosmology. Either way, I haven't read any Turok papers in ages. Although his did some great work in the 90s on the cosmic microwave background, since then he's become something of a miniature celebrity and a bit of a joke among some colleagues and collaborators around here, although he's the boss now so shhh.

Last edited by Jigglefactor on Sat Sep 10, 2011 12:15 pm, edited 1 time in total.

I'm not the slightest bit knowledgeable about dark matter experiments or the sorts of statistical analyses that go into these, so take this with a grain of salt, but for my money there isn't anything particularly special here. In my skimming of the paper (http://arxiv.org/PS_cache/arxiv/pdf/110 ... 0702v1.pdf for the brave), that is mostly just looking at graphs, this particular one seems at odds with several other proposed dark matter detections (of which many are also at odds with each other). Figured I'd post this anyway since dark matter is a hot topic and it would have come up eventually.

"It's fun to think about but would actually violate some very principal laws of physics (it's a bit technical and not particularly plausible. Wormholes on the other hand could work, but we won't know until the physics of quantum gravity are understood."

Jigglefactor......are you aware of what you just wrote?You seem to only validate what you deem appropriate. Nothing against you bro but I can't take you serious after that comment.

The Gravity Recovery and Interior Laboratory (GRAIL) is an American lunar science mission in NASA's Discovery Program, which will use high-quality gravitational field mapping of the Moon to determine its interior structure.

Quote:

Unlike the Apollo program's missions, which took three days to reach the Moon, GRAIL will make use of a three- to four-month low-energy trans-lunar cruise via the Sun-Earth Lagrange point L1 to reduce fuel requirements, protect instruments and reduce the velocity of the two spacecraft at lunar arrival to help achieve the extremely low 50 kilometers (31 mi) orbits with separation between the spacecraft (arriving 24 hours apart) of 175–225 kilometers (109–140 mi)

"It's fun to think about but would actually violate some very principal laws of physics (it's a bit technical and not particularly plausible. Wormholes on the other hand could work, but we won't know until the physics of quantum gravity are understood."

Jigglefactor......are you aware of what you just wrote?You seem to only validate what you deem appropriate. Nothing against you bro but I can't take you serious after that comment.

I know exactly what I wrote. A wormhole has nothing to do with a black hole. Back in the 70s when physicists realized black holes couldn't work like a tunnel through spacetime, a lot of research was done on wormholes (mainly by Kip Thorne and co.). That is to say solutions of Einstein equations containing not black holes, but just normal looking tunnels through spacetime which turned out to have their own completely unrelated problems (such as needing matter with negative mass). Throw in a little quantum field theory and the entire thing gets even more convoluted.

Regardless, while I may seem like I'm consistently trying to be a contrarian, I'm just trying to weed out some common misconceptions since I actually work in the field. If you don't feel like listening, fine. I was just trying to help since you seemed terribly confused.

EDIT:

droneriot wrote:

Here's a video of the lunar orbiter GRAIL (Gravity Recovery and Interior Laboratory) launching into space:

I like this kind of theories. The very distant past is always subject to strangeness, and this particular theory is just that.

Quoting a post from early August because the GRAIL mission launched today may help finding evidence for or against the theory the article above is talking about. To quote BBC's own news story about GRAIL:

Quote:

Another fascinating idea to emerge recently that will come under scrutiny from the Grail "microscope" is the suggestion that the highlands on the farside were formed as a result of a low-velocity impact by a second, much smaller moon.

A research team published a paper in the journal Nature last month that showed how such an impact could have added material to the crust on the far hemisphere.

"When I first saw the paper I thought it was outlandish, but as I read the paper I realised that the simulations that were done were very well thought out, and they made specific, testable predictions that could be addressed by studying data that will be obtained with Grail," said Dr Zuber.

"It's fun to think about but would actually violate some very principal laws of physics (it's a bit technical and not particularly plausible. Wormholes on the other hand could work, but we won't know until the physics of quantum gravity are understood."

Jigglefactor......are you aware of what you just wrote?You seem to only validate what you deem appropriate. Nothing against you bro but I can't take you serious after that comment.

I know exactly what I wrote. A wormhole has nothing to do with a black hole. Back in the 70s when physicists realized black holes couldn't work like a tunnel through spacetime, a lot of research was done on wormholes (mainly by Kip Thorne and co.). That is to say solutions of Einstein equations containing not black holes, but just normal looking tunnels through spacetime which turned out to have their own completely unrelated problems (such as needing matter with negative mass). Throw in a little quantum field theory and the entire thing gets even more convoluted.

Regardless, while I may seem like I'm consistently trying to be a contrarian, I'm just trying to weed out some common misconceptions since I actually work in the field. If you don't feel like listening, fine. I was just trying to help since you seemed terribly confused.

EDIT:

droneriot wrote:

Here's a video of the lunar orbiter GRAIL (Gravity Recovery and Interior Laboratory) launching into space:

Awesome, I hadn't even heard about this before. I should really pay more attention to what experimentalists are up to nowadays.

I'm beyond ecstatic that you want to help me and I really mean that. I'll admit I'm extremely curious and as far as me being confused,well yes,I confess ,I do not have a degree in quantum physics but whats even more confusing is the fact that most of what I'm interested in is based on theories. From what I've read, the last data from Cern, in Geneva, shows that physicists could not find the long sought after "God" particle where they were expecting to find it. So, my question is, does this not change our general understanding of the natural world? or to be more precise, the laws of physics?Can you see where someone like myself can question research based on theories that have yet to be confirmed. I honestly want to understand the universe as much as my uneducated mind can fathom. Again, I must ask you to be patient and understand that I question the science that is constantly being updated on what seems like a yearly/monthly basis.

The hypothesis hunglikemouse is referring to - that black holes send matter and energy to newly created universes - is very interesting and plausible.

It's fun to think about but would actually violate some very principal laws of physics (it's a bit technical and not particularly plausible). Wormholes on the other hand could work, but we won't know until the physics of quantum gravity are understood.

I appreciate your input. You obviously know much more than I do here, but would it be possible to expand on this a bit without getting too technical? With our extremely limited knowledge on singularities, what do we know that makes this not even a slightly plausible theory? What laws are violated and how?

But they have found that is not so and it appears everything is actually speeding up, accelerating away which they put down to "dark energy" (different from dark matter). Maybe all matter travelling at colossal speed encounters other regions we yet know nothing about?

No, this is a misunderstanding of how the universe expands. Many people imagine this expansion as galaxies and the like flying out into empty space beyond the universe, but this is incorrect. The universe encompasses all space and time, there is no region outside of it to expand into (ignoring theories of multiple universes for the sake of this explanation, but in any case these other universes would not be simply far away regions that you get to by flying for a long time). Rather, it is space itself that is expanding; the universe is stretching if you will, its internal distances increasing.

A popular analogy is that of a balloon on which you draw a few dots while it's not inflated, then as you blow air into the balloon you can observe that the dots are all "moving" away from each other, even though they're not really going anywhere - it's the balloon's surface between them that is stretching. So it is with the universe; objects are observed to be moving away from each other as the space between them itself is expanding. It's an imperfect analogy of course; the balloon is a two-dimensional surface and it's expanding into the air around it, while the universe has three spatial dimensions, but hopefully you get the idea.

I am familiar with the balloon analogy. I was trying to push my self to imagine if our universe arose from an instantaneous event why not others? at different times - why should ours be unique? Like in an accelerator where particles collide, maybe the matter in our Universe is accelerating to ultimately collide with matter travelling toward us from other "regions"? Maybe we`re in one vast accelerator?

I`ve just read this article which also suggests the plausibility of other Universes which could possibly be linked to ours.

Quote:

Wormholes are warps in the fabric of space-time that connect one place to another. If you imagine the universe as a two-dimensional sheet, you can picture a wormhole as a "throat" connecting our sheet to another one. In this scenario, the other sheet could be a universe of its own, with its own stars, galaxies and planets.

From what I've read, the last data from Cern, in Geneva, shows that physicists could not find the long sought after "God" particle where they were expecting to find it. So, my question is, does this not change our general understanding of the natural world? or to be more precise, the laws of physics?

They haven't found it yet. Much of the data collected so far hasn't been analyzed and they haven't even gone to full power yet. What they have done so far is put even more stringent restraints on the mass of the higgs boson. Eventually they may find it or rule it out. Even if it isn't there, it doesn't change ALL the laws of physics, the higgs mechanism is just the simplest way they could come up with to generate mass. If there ends up not being one then they turn to some of the higgsless models that have been proposed or come up with new ones.

hunglikemouse wrote:

Can you see where someone like myself can question research based on theories that have yet to be confirmed. I honestly want to understand the universe as much as my uneducated mind can fathom. Again, I must ask you to be patient and understand that I question the science that is constantly being updated on what seems like a yearly/monthly basis.

I can definitely understand that drive to ask questions. Popular science books are one option, although I haven't read any myself so I can't vouch for any particular. There are also some pretty good science blogs out there like http://profmattstrassler.com/ who tries to explain much of particle physics, the LHC and has pretty up to date news on data that comes out. For more cosmology related stuff there's Sean Carrol's blog http://blogs.discovermagazine.com/cosmicvariance/, although his posts cover more than just physics. I'm sure with some googling you could find some decent blogs by academics on various subjects.

Moravian_black_moon wrote:

I appreciate your input. You obviously know much more than I do here, but would it be possible to expand on this a bit without getting too technical? With our extremely limited knowledge on singularities, what do we know that makes this not even a slightly plausible theory? What laws are violated and how?

I started writing a big thing explaining this from the point of view of conservation of information (which is what I meant by violating an important physical principal), but thinking about it some more that doesn't even matter and is really just a simple consequence of regular old general relativity (I blame sleep deprivation for this oversight). There are actually black hole solutions that would let you go through them (avoiding the singularity) and coming out into another universe (for example rotating and/or charged black holes). If you look back on the bottom of page 4 I believe, I explained why this ends up not working (Yeah, I'm lazy).

As for the nature of singularities, they're not some big mystery. A singularity is just a point (or ring) in spacetime where the curvature of spacetime goes to infinity, that is the gravitational force grows infinitely and would condense everything. The only problem with this is that we know from quantum mechanics that not all matter can be condensed this way so we have to find some new theory that hopefully stops gravity from growing infinitely. There's nothing about singularities that really has anything to do with other universes.

Sorry if none of this is coherent, I haven't slept since Friday morning.

EDIT:

mindshadow wrote:

Like in an accelerator where particles collide, maybe the matter in our Universe is accelerating to ultimately collide with matter travelling toward us from other "regions"? Maybe we`re in one vast accelerator?

Not quite. Everything in the universe is accelerating away from everything else (on very large scales), that's what's meant when saying that the expansion of the universe is accelerating. It isn't accelerating in any particular direction or to any particular place.

There is a theory called Brane-world gravity where our universe would just be one of many all floating in a higher dimensional bulk which you might be interested in, although this wouldn't necessarily have anything to do with the expansion of the universe. Like hunglikemouse posted earlier, it's in just such a scenario that Neil Turok, et al. came up with a way to describe big bangs using collisions between different universes in this higher dimensional bulk.

As for the nature of singularities, they're not some big mystery. A singularity is just a point (or ring) in spacetime where the curvature of spacetime goes to infinity, that is the gravitational force grows infinitely and would condense everything. The only problem with this is that we know from quantum mechanics that not all matter can be condensed this way so we have to find some new theory that hopefully stops gravity from growing infinitely. There's nothing about singularities that really has anything to do with other universes.

I understand this and I'm not aware of anybody in this thread that was drawing a conclusion between singularities and a multi-verse. My first and foremost interest has to do with Orvut's theory which would explain the effects of dark matter where areas of the universe are heavier than they should be given everything that's present. With this theory, dark energy is no longer a mysterious unknown quantity, but rather an extra gravitational force that drives the universe to universe interaction. To me, this seems like an extremely plausible theory and kills a few birds with one cosmic stone,so to speak ,and in turn locking in past research without it having all been done in vain.I hope this makes sense, I know of only one way to make my thoughts luminescent.

I understand this and I'm not aware of anybody in this thread that was drawing a conclusion between singularities and a multi-verse. My first and foremost interest has to do with Orvut's theory which would explain the effects of dark matter where areas of the universe are heavier than they should be given everything that's present. With this theory, dark energy is no longer a mysterious unknown quantity, but rather an extra gravitational force that drives the universe to universe interaction. To me, this seems like an extremely plausible theory and kills a few birds with one cosmic stone,so to speak ,and in turn locking in past research without it having all been done in vain.I hope this makes sense, I know of only one way to make my thoughts luminescent.

My little rant on the nature of singularities was more so addressed to Moravian's assertion that we understand very little about them.

As for Ovrut et al.'s theory, I haven't actually read the theoretical papers behind these because they're long, I'm lazy and my string theory isn't up to par these days. From what I could gather from certain experimental papers is that with a bit of tuning they can recreate the results from our current model of cosmology (The lambda cold dark matter model) while solving the problem of the big bang singularity, the initial flatness, the homogeneity of the universe, dark matter, etc.

The problem with this is that it's all based on string cosmology and brane-brane interactions, something we have absolutely zero evidence for and even if they do exist they might not work at all like these guys thought they would. It would certainly be nice if everything fit into a neat little package like this but there's a long way to go before any of this becomes anything more than speculative.

John Wheeler at the University of Texas, who has been called the physicist’s physicist, has expanded on the anthropic idea and envisions an ensemble of universes in endless cycles of cosmic expansion and contraction. This takes place in an arena he calls ‘superspace’, an infinitedimensional space in which every point can correspond to the entire geometry of a universe.